Abstract
The changes of moisture content during drying are experimentally investigated in the present work. Particular emphasis is placed on the initial stage of drying of saturated concrete, when moisture contents are high, since the resistance of the material to several deterioration processes is reduced at high moisture content levels, and experimental data for this stage of drying is lacking.
The experimental investigation is performed for concrete cylinders of different lengths with one end exposed to drying. In this way, moisture flow is forced to be unidirectional. The gravimetric method is employed to obtain moisture content distribution in the material at different times of drying. The cylinders are made of lightweight concrete with varying water-to-cement ratios and moist curing times, and the influence of these variables upon the drying process is assessed. Higher initial water content and more rapid changes of water content occur in lightweight concrete with a higher w/c ratio. An increased moist-curing period results in a decrease of drying rates throughout the drying process.
Résumé
Dans ce travail, on procède à une étude expérimentale des modifications de la teneur en eau au cours du séchage. On s'attache particulièrement à la phase initiale du séchage du béton saturé, où les teneurs en eau sont élevées, étant donné que la résistance du matériau à plusieurs processus de détérioration est réduite pour des teneurs en eau élevées et que les données expérimentales font défaut pour cette phase du séchage.
L'étude est effectuée sur des cylindres de béton de longueurs différentes dont l'une des extrémités est exposée au séchage. De cette façon, l'écoulement d'eau est forcément unidirectionnel. On utilise la méthode gravimétrique pour obtenir une distribution de la teneur en eau à différents moments du séchage. Les cylindres sont confectionnés avec du béton léger, les rapports eau/ciment et les durées de cure humide étant variables; on évalue l'influence de ces variables sur le processus de séchage. Avec un rapport eau/ciment plus élevé, on constate, dans le béton léger, une teneur en eau initiale plus importante et des modifications de teneur en eau plus rapides. L'accroissement de la durée de cure se traduit par une diminution des vitesses de séchage au cours du processus de séchage.
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References
Hanson, J.A., ‘Effect of curing and drying environments on splitting tensile strength of concrete’,ACI Journal,65 (1968), 53–543.
Galloway, J.W., Harding, H.M. and Raithby, K.D., ‘Effects of moisture changes on flexural and fatigue strength of concrete’, Transport and Road Research Laboratories, Report 864, UK (1979), 26 p.
Bazant, Z.P. and Kim, J., ‘Consequences of diffusion theory for shrinkage of concrete’,Mater. Struct.,24 (1991), 332–326.
Hall, C., Hoff, W.D., and Nixon, M.R., ‘Water movement in porous materials—VI: evaporation and drying in brick and block materials’,Building Environ.,19 (1) (1984), 1–20.
Harmathy, T.Z., ‘Simultaneous moisture and heat transfer in porous systems with particular reference to drying’,I & EC Fundamentals,8 (1) (1969), 92–103.
McCabe, W.L. and Smith, J.C., ‘Unit Operations of Chemical Engineering’ (McGraw Hill, New York, NY, 1976).
Ooi, O.S., ‘Aggregate saturation in lightweight concrete’, M.Sc. Thesis, University of New Brunswick, Canada (1988).
Sakata, K., ‘A study on moisture diffusion in drying and drying shrinkage of concrete’,Cem. Conc. Res.,13 (1983), 216–224.
Parrott, L.J., ‘Factors influencing relative humidity in concrete’,Mag. Concr. Res.,43 (154) (1991), 45–52.
Penev, D. and Kawamura, M., ‘Moisture diffusion in soil-cement mixtures and compacted lean concrete’,Cem. Concr. Res.,21 (1991), 137–146.
Hashida, H., Tanaka, K. and Koike, M., ‘Moisture distribution in concrete before and after application of the finish’,Building Research and Practice,5 (1990), 303–308.
CSA Standard A23.2-6C, Density, yield and cementing materials factor of plastic concrete, Canadian Standard Association, Rexdale, Canada (1977).
CSA Standard A23.2-5C, Slump of concrete, Canadian Standard Association, Rexdale, Canada (1977).
CSA Standard A23.2-7C, Air content of plastic concrete by the volumetric method, Canadian Standard Association, Rexdale, Canada (1977).
Šelih, J., ‘Movement of water during drying of saturated concrete’, Ph.D. thesis, University of New Brunswick, Canada (1994).
Kosmatka, S.H., Panarese, W.C., Allen, G.E., Cumming, S., ‘Design and control of concrete mixes’, (Canadian Portland Cement Association, Ottawa, Canada, 1991).
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Editorial note Dr. Jana Šelih is working at the Institute of Materials in Ljubljana, Slovenia, which is a RILEM Titular Member. Prof. T.W. Bremner is a RILEM Senior Member.
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Šelih, J., Bremner, T.W. Drying of saturated lightweight concrete: an experimental investigation. Mat. Struct. 29, 401–405 (1996). https://doi.org/10.1007/BF02485989
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DOI: https://doi.org/10.1007/BF02485989